The interior and Exterior angle are complementary angles, which mean when added together, they equal 180 degrees. -So we know in order to find the exterior, we subtract the interior angle (65 degrees) from 180 (straight angle) and we get the exterior angle, which is 115 degrees.
Isosceles triangle/exterior angle problem explained
Interior and Exterior Angles including Isosceles Triangles
Vertex angle of an Isosceles Triangle-Geometry Help
Frequently Asked Questions
Are all isosceles triangles 180?
Explanation: Every triangle has 180 degrees. An isosceles triangle has one vertex angle and two congruent base angles. Thus the vertex angle is 38 and the base angle is 71 and their sum is 109.
Do all angles of an isosceles triangle add up to 180?
If you are given one interior angle of an isosceles triangle you can find the other two. ... We know that the interior angles of all triangles add to 180°. So the two base angles must add up to 180-40, or 140°. Since the two base angles are congruent (same measure), they are each 70°.
Is the base of an isosceles triangle congruent?
Isosceles triangle theorem. Isosceles triangle theorem, also known as the base angles theorem, claims that if two sides of a triangle are congruent, then the angles opposite to these sides are congruent.